Internal-combustion engine.



'LQQAQO W. McHARRY. INTERNAL COMBUSTION ENGINE. APPLICATION FILED JUNE \0. ms.

Patented Dec. 31, 1918.

WILLIAM McHARRY, 0F COLCHESTER, ENGLAND.

INTERNAL-COMBUSTION ENGINE.

Specification of Letters Patent.

Patented Dec. 31, 1918.

Application filed June 10, 1918. Serial No. 239,272.

To all whom it may concern: I

Be it known that I, WILLIAM Mel-Inner, a subjet of the King of England, residing at Colchester, Essex, England, have invented certain new and useful Improvements in Internal-Combustion Engines, of which the following is a specification.

This invention relates to two-stroke cycl internal-combustion engines and has for its object to provide an engine of this type which shall have greater flexibility of load than those at present in use. Usually the exhaustand inlet-ports of these engines are controlled by the piston, with the result that the only means for varying the charge for different loads is a throttle for varying the supply of gas and air to the pump-chamber. It has also been proposed to release through a specially controlled valve, a portion of the explosive charge either to waste or to by-pass it from the engine-cylinder back to the pump-chamber, but all these methods of running result in ex essive temperature of the charge previous to compression, at light loads, and undue dilution of the charge with inert gases as well as waste of fuel.

According to this invention, a two-stroke cycle engine having inletand exhaust-valves and operating-mechanism therefor, is characterized by the said operating-mechanism being so constru'ted that it can be adiusted at will or by automatic means while the engine is running, to cause the exhaust-valve to remain open during a greater or smaller angular movement of the crank-shaft and the inlet-valve to open always at such time before the closing of the exhaust-valve as will permit the deliverv of the charge into the ylinder to be completed approximately at the moment of closing the said exhaustvalve. for the purpose of giving flexibility of load without the disadvantages referred to above.

Any suitable me"hanism may be employed for operating the valves in the manner described, provided su h mechanism can be adjusted at will or bv automatic means according'to the variations of load.

A simple form of mechanism is shown in the a companying drawings wherein Figure 1 is a se"tion throu h the valvemechanism on the axis of rotation of the operating-shaft, and

Fi 2 shows the parts illustrated in Fig. I viewed from the right of that figure.

The same letters indicate the same parts In both figures of the drawings.

The mezhanism shown can be 'applied to any convenient construction of engine and can be attached to the side of such engine by bolts passed through the circular casting In the casting, t'appet-rods B, B are mounted so that they can slide vertically. Resting upon the tops of the tappet-rods are the stems C, C of exhaustand inletvalves respectively, which may be of the puppet type and may be kept closed by springs. The lower ends of the tappet-rods enter a chamber A in'the casing A and bear against a cam-member D which is carried by a shaft D whi h extends through the chamber A The shaft is coupled to, or is an extension of the engine crank-shaft and rotates at the same speed as the crankshaft. The cam-member D can slide on the shaft D but has driving connection therewith by means of the feather D. On the shaft are two cams D and D respe tively. The cam D has an opening edge 05 which is parallel with the axis of rotation of the shaft .D and a closing edge 07 which follows a helical line relatively to the shaft 1). Both edges of the cam D are helical and the closing edge conforms with the closing edge of the cam'D To slide the cam-member D, an operatingrod E is provided, having a fork E which engages a circumferential channel D in the cam-member.

The bottom ends of the rods B, B carry rollers B B", wh ch bear against the cammember against which they are thrust by the springs of the valves which press the stems C, C down upon the tappet-rods.

The operation of this mechanism is as follows:

With the parts in the position shown in Fig. 1, the mechanism is arranged for full load. The position of the crank-pin relatively to the cams D and D is indicated at F, Fig. 2, and it will be seen that the cam D will open the exhaust-valve C when the crank-pin is about 40 from the bottom deadcenter. At about the (lead-center, the cam D will commence to open the inlet-valve C and the two valves will close simultaneously when the crank-pin arrives at about 40 on the other side of the deadcenter. With the cam-member D in this position, the exhaustvalve is open for the smallest angular movementof the crank-shaft for which the mechanism allows, but as the member D is slid to the right of Fig. 1 by operating the rod E, (which can be done either by hand or by known automatic governing means) as the load decreases, the valve remains open for a greater angular movement of the crank-shaft though it always opens with the crank-shaft in the same angular position because the edge dis straight. The width of the cam D is sufiicient to allow the delivery of the charge into the engine-cylinder to be completed approximately at the moment of closing the exhaust-valve so that this is arranged to open the inlet-valve when the crank-shaft is at different angular positions which depend upon the 'position the shaft will occupy at the moment the exhaustvalve closes. T he opening and closing sides of the cam D need not be parallel.

It will be seen that the member E can be operated freely while the engine is running and that the mechanism for operating the valves in the manner described may be easily arranged so that for any particular engine when running at maximum load, the exhaust-valve may be made to remain open for a third of the compression-stroke of the piston so that the expansion-stroke is a third greater than the compression-stroke, which gives high thermal efliciency.

What I claim as my invention and desire to secure by Letters Patent is In a two-stroke cycle engine, the combination of inletand exhaust-valves, operatingmechanism therefor, and means whereby the operating-mechanism can be adjusted while the engine is running to cause the exhaust to remain open during a greater or smaller angular movement of the crank-shaft according to load and to simultaneously cause the inlet-valve to open always at such time before the closing of the exhaust-valve as will permit the delivery of the charge into the cylinder to be completed approximately at the moment or" closing the said exhaustvalve for the purpose described.

In testimony whereof I afiix my signature.

WILLIAM MOHARRY. 

